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Expert claims RDI of vitamin D ten times too lowProfessor Anthony Norman of the University of California, along with other academics, has called for a review of government policy guidelines on recommended intakes of vitamin D.
"It is becoming increasingly clear to researchers in the field that vitamin D is strongly linked to several diseases. It's biological sphere of influence is much broader than we originally thought" Norman explained, drawing on his 45 years of experience researching the vitamin. Vitamin D is known as the "sunshine vitamin" as it is synthesised in the skin upon exposure to ultraviolet-B (UVB) radiation from sunlight; it is a fat soluble vitamin most famous for its role in preventing rickets in children. The circulating form of the vitamin is 25-hydroxyvitamin D, the active form of the vitamin is 1, 25-dihydroxyvitamin D (1,25(OH) 2D). In vitamin D deficiency, calcium absorption is insufficient to satisfy the body's calcium needs, with devastating consequences for bone health. Recent evidence however suggests that the role of vitamin D is far more complex and vital than maintaining calcium levels. More than 50 genes in tissues throughout the body are known to be regulated by 1,25(OH) 2D. 36 different cell types have receptors to which vitamin D will bind. Vitamin D deficiency may contribute to conditions such as cancer, hypertension, insulin resistance and poor immunity. The vitamin is found in a limited number of foods, namely egg yolks, dairy and oily fish, thus we are dependant on sun exposure to prevent deficiency. Current recommendations are that supplements of 200-400IU (5-10μg) of vitamin D should be used by the elderly and those with minimum sun exposure; Norman advocates a recommended daily intake of 2000IU. To read the abstract of Professor Norman's paper click here. |